configure: define CONFIG_THIS_YEAR at the configure level

The macro value can be shared between configure script and cmdutils.c.

cmdutils.c

@@ -69,7 +69,7 @@ struct SwsContext *sws_opts;
 AVDictionary *swr_opts;
 AVDictionary *format_opts, *codec_opts, *resample_opts;
 
-const int this_year = 2013;
+const int this_year = CONFIG_THIS_YEAR;
 
 static FILE *report_file;
 

configure

@@ -4919,6 +4919,7 @@ cat > $TMPH <<EOF
 #define FFMPEG_CONFIG_H
 #define FFMPEG_CONFIGURATION "$(c_escape $FFMPEG_CONFIGURATION)"
 #define FFMPEG_LICENSE "$(c_escape $license)"
+#define CONFIG_THIS_YEAR 2013
 #define FFMPEG_DATADIR "$(eval c_escape $datadir)"
 #define AVCONV_DATADIR "$(eval c_escape $datadir)"
 #define CC_IDENT "$(c_escape ${cc_ident:-Unknown compiler})"